Field
The disclosed concept relates generally to circuit breakers, and in particular, to trip units for use in circuit breakers. The invention further relates to access doors for use in trip units.
Background Information
Circuit interrupters, such as for example and without limitation, circuit breakers, are typically used to protect electrical circuitry from damage due to an overcurrent condition, such as an overload condition, a short circuit, or another fault condition, such as an arc fault or a ground fault. Circuit breakers typically include separable contacts. The separable contacts may be operated either manually by way of an operator handle or automatically in response to a detected fault condition. Typically, such circuit breakers include an operating mechanism, which is designed to rapidly open the separable contacts, and a trip mechanism, such as a trip unit, which senses a number of fault conditions to trip the breaker automatically. Upon sensing a fault condition, the trip unit trips the operating mechanism to a trip state, which moves the separable contacts to their open position.
Some trip units include an access door which allows for easy access to switches which control trip unit settings without requiring removal of one or more covers which are typically secured to a housing of the circuit breaker via screws or other suitable fasteners. Such access doors are typically formed from a clear plastic material. Such construction provides a number of benefits. One of such benefits of utilizing such a clear material is that the switches covered by such access doors and thus the settings thereof may be readily viewed without requiring the access door to be opened. Another benefit of using such material is the generally low cost of the material and forming thereof.
While there are a number of benefits of such present designs, there is still room for improvement as access doors tend to be less than durable and may be rather easily broken if care is not taken. Typically, such breakage occurs when a technician is installing and/or servicing a circuit breaker and thus has the front cover removed. During such time, it is common to have the access door of the trip unit open for making adjustments to the unit. Being formed from clear material, the access door tends to not stand out and can be easily left in an open position. When disposed in the open position, the access door is generally fragile and can be rather easily broken, typically at the hinged portion thereof, if opened beyond its intended range. Such over-opening may readily occur if the access door is contacted while disposed in an open position such as by a technician moving in the vicinity of the access door or by attempting to install the front cover without having first closed the access door.
There is thus room for improvement in access doors for trip units.
There is also room for improvement in trip units employing access doors, and circuit breakers employing such trip units.